A data diode device is a network relay device that causes data to flow through a communication path of a gateway in only one direction for security countermeasures. By blocking data flow in the opposite direction, a connection device can be defended against a virus attack and hacking.
In addition, since the data diode device is a network relay device, it is necessary to reduce packet loss in the data diode device.
In a conventional network relay device, two-way communication including a transmission side network and a receiving side network is provided. Thus, in a system in which security countermeasures are required, unnecessary communications from the outside are interrupted by a firewall.
However, in recent years, for a system in which a higher level of security is required, a data diode device is developed as a network relay device for achieving complete one-way communication.
Further, a conventional network relay device is capable of detecting packet loss due to IP packet congestion; in this case, the IP packet congestion is resolved by suspending the communication by a pause frame and the like (see Patent Literature 1).